In addition to being the subgroup with the highest HIV incidence, men who have sex with men (MSM) are also disproportionately affected by other sexually transmitted infections (STIs) which make it more likely for HIV transmission to occur. For example, in 2012, MSM accounted for three-quarters of all primary and secondary syphilis infections11. Additionally, MSM were found to be more likely to be infected with strains of gonorrhea which are resistant to antibiotic drugs20,29. Evidence further suggests that a racial disparity within the MSM community may exist where Blacks and Hispanics have shown a steeper increase in STI infection relative to their non-Hispanic white counterparts 53. In addition to being disproportionately affected by STIs, recent empirical work has also suggested that nearly one-in-three MSM has experienced childhood sexual abuse (CSA)37. CSA has been associated with increased use of avoidance coping50 and substance use37,41 in order to remedy negative affect. It has also been linked to increased PTSD symptom expression38. Each of these individual-level psychological variables is thought to be a determinant to STI infection as they've been linked to STI acquisition and transmission16,52,44. However, these psychological factors alone fail to account for the ways in which systemic social factors may play a role in disproportionate rates of STI infection 12. Structural factors such as poverty, unstable housing, and neighborhood crime have also been linked to increased sexual risk3, 15, 30, 35.These social determinants have also been associated with STI infection 1, 6, 35. The current proposal seeks to investigate both psychological (avoidance coping, substance use, and PTSD symptomology) and social (poverty, unstable housing, and neighborhood crime) determinants and relate them to sexual risk and STI infection both cross-sectionally and longitudinally among high-risk MSM with histories of CSA. The proposal seeks to model baseline interrelationships between psychological/social determinants and sexual risk (Aim 1) and self-reported STI infection in the past year (Aim 2). We will evaluate the effects of racial identity on these relationships. It then seeks to longitudinally examine the impact of psychological and social determinants on the trajectory of sexual risk over 12 months (Aim 3). Lastly, the proposal will employ a prospective longitudinal design to examine how psychological/social determinants affect likelihood of acquiring an STI over the course of 12 months (Aim 4). Findings from this study may better inform us of relative risk associated with psychological and social determinants. This can be used to design structural interventions aimed at reducing the disparity in STI incidence for MSM.